The present invention relates to a device for varying the distance or "pitch" between the seats in commercial aircraft.
Commercial aircraft are equipped with longitudinal rails on the floor of the cabin for fixing the passengers' seats. The principle of the connections enables a determined position to be chosen for each seat individually, as a function of the available space and the number of seats.
The distance or the "elementary pitch" between each possible position being universally standardised at 25.4 mm, the resultant "pitch" of the seats is necessarily a whole number of "elementary pitches".
Although they allow a choice of positions, the rails and connections of heretofore known seats are not designed to allow a simple, continuous longitudinal movement of the seats. At the most, their position may be locally adjusted by a few centimeters. It is impossible to change the position of all the seats in a cabin without disconnecting them from the rails one by one, transporting them manually and refixing them in their new position.
This lack of flexibility is due to several reasons, namely:
1. each seat abuts on two rails; PA1 2. the connections of the seats are not designed to slide easily in the rails and the latter are themselves often encumbered with various objects which prevent sliding; and PA1 3. when it is desired to move a seat, this can only be done by applying forces thereon above the level of the rails. PA1 1. place the bolt in a high position by means of its cam; PA1 2. introduce all the lugs (6 in all) simultaneously at the desired spot in the holes in the rail; PA1 3. displace the whole seat by half an elementary pitch forwards or backwards, so as to locate the bolt in the axis of the desired hole; and PA1 4. rotate the cam so that the bolt descends into the corresponding hole.
Because of this manual work, it is impossible to balance the efforts on each foot so as to displace them simultaneously. This inevitably results in the seat jamming in the rails and the movement being stopped. More particularly, the longitudinal rails on which the seats are fixed are each provided with a longitudinal groove of dovetail shape. Vertical holes are made in the inner lips of the rail at very regular intervals. Furthermore, the feet of the seats comprise, at the front and rear, lugs which are conical at the base and which may penetrate into the longitudinal rail through one of the holes provided to this end in the opposite lips and which may then be connected thereto after a displacement equal to half an elementary pitch. At the rear, the foot of the seat comprises a vertical bolt which is introduced into one of the holes in the rail after displacement of the foot by half an elementary pitch.
With such a connecting device, the following steps must be taken on each of the two feet when it is desired to fix a seat on the rail:
To dismantle a seat, these operations are reversed. When a seat is to be displaced by a few elementary pitches, this known device does not enable this operation to be carried out easily, because the efforts exerted on the seat added to the inevitable deformations of the structure of the seat are very frequently the cause of one or more lugs becoming disengaged from the rail, which lugs tend to lift out of the rail, upon passage in the axis of a hole.